Medical infusions are injected into bag-shaped containers, e.g., infusion bags and then are transported and stored.
Such a bag filled with a medical infusion contains nitrogen gas to prevent the oxidation and degradation of the infusion. After a bag is filled with an infusion, the oxygen concentration of the infusion is measured to inspect whether the infusion is defective or not. In other words, it is naturally preferable that less oxygen is entrained during manufacture, and thus when the oxygen concentration is higher than a permissible value, it is decided that the product is defective.
This inspection is conducted by a destructive method in which an injection needle is inserted into a product bag serving as a sample and air is collected to measure the oxygen concentration. After the inspection, the sample is discarded. Since the inspection is not a one hundred percent inspection but a sample inspection, safety and sanitation may not be secured.
For products in vial containers other than products in infusion bags, a method is available in which oxygen entrained or present in a container in the manufacturing process is detected by a laser beam (e.g., see National Publication of International Patent Application No. 2007-508567).
Specifically, in this method, a laser beam is transmitted to a gas phase portion on the top of a vial container and the amount of transmitted light is measured. In other words, the absorbance is detected to measure an oxygen concentration.